Two piece thermoplastic coated paper cups of the type produced by previous machines are made up from a side wall blank and a circular bottom wall blank. Typically the machine at which the blanks are assembled includes a turret mounted on a vertical axis and having a number of mandrels projecting radially outwardly from the turret axis. The turret is intermittently stepped to rotate the mandrels to each of a number of work stations. In the operation of the machine, a flanged bottom wall blank is concentrically attached by suction to the end surface of each mandrel, a side wall blank is wrapped around the mandrel and the edges bonded together to form a seam. A flange on the bottom wall blank is then bonded to a flange on the end of the side wall blank to seal the bottom.
In U. S. Pat. No. 4,490,130, issued Dec. 25, 1984, to Daryl R. Konzal, et al., entitled, "Machine For Forming Seams Of Two-Piece Paper Cups," a machine is described for making two-piece flat bottom paper cups of thermoplastic coated papers, each including a side wall blank and a disc-like bottom wall blank. In this machine, the disc-like bottom wall blank is of circular cross section and temporarily held against a flat outwardly facing surface of the mandrel by a vacuum. The edges of the circular blank extend outwardly from the end of the mandrel and are folded to form a flange. A separate turret is provided for feeding the side wall blanks to the main turret, which requires heating of the bottom edge of one end of the blank at one station and heating the top of the edge at the other end of the blank at a second station prior to wrapping the blank around the mandrel. The side wall blank is then wrapped around the mandrel so that the heated edges overlap and are sealed. The bottom edge of the blank extends beyond the end of the mandrel and overlaps the flange of the bottom wall blank. Heaters are provided for heating the thermoplastic coating on the flange portions of the blanks to provide for their adhesion to one another when folded inwardly against the bottom of the mandrel. This application was concerned primarily with a system for separately heating the bottom edge of one end of the blank and the top edge of the other end of the blank with hot air prior to wrapping the blank around the mandrel.